The present invention relates generally to fibrous products and a method of making same, and more particularly to an improved polishing/grinding product and method of manufacture thereof.
Products made in accordance with the present invention can be utilized for a number of various applications such as polishing, grinding, wicking and the like. The present application describes the improved product and method with respect to a polishing product, such as utilized for metal polishing, but it should be understood by one of ordinary skill in the art that there are a number of suitable applications for the present invention, including but not limited to those set forth above.
Many attempts have heretofore been made to fabricate pads for polishing and/or grinding of various and sundry shapes and materials to accommodate for the wide variety of uses noted above, and in general, have succeeded in affording some economic and/or technical improvement in the then state of the art processes. Though such improvements have heretofore been made, problems continue to exist for various and sundry reasons. Notably, needled natural and synthetic fibrous felts have been produced and utilized as polishing pads though historically such products have been lacking in uniformity of density, porosity, and the like. Furthermore, historically there have been limits to the thickness of such needled fibrous products though attempts have been made to tack plural layers together to build up a thicker composite polishing pad.
Other attempts have been made to produce composite pads in which discrete fibrous layers have been adhesively secured together. Again, the adhesive interfacial layers present a different effect in the working of abrasives or the like across a work surface than the fibrous pad, leading to possible changes in surface characteristics. Likewise, adhesive bonds are subject to fail, leading to delamination with same attendant results as noted above.
In recent years, following at least the advent of the poromeric synthetic leather materials the fibrous pads or substrates have been impregnated with porous elastomeric materials. The elastomeric materials employed have often been urethane based and have been variously applied to the fibrous materials from both solvent and aqueous systems. Such materials are adequate for many tasks. However, upon prolonged work at elevated temperatures, the elastomeric materials which are thermoplastic in character tend to fuse together and glaze over the work surface of the product. Such glazing over hinders further grinding or polishing and the product becomes ineffective for its intended use.
Currently, polishing products such as wheels, and the like, are manufactured from non-woven substrates by die cutting to the desired shape or by lamination with adhesive between adjacent layers of material followed by cutting the substrate to the appropriate shape. The laminating process is more efficient from a material standpoint in that there is little if any wasted substrate material. In addition, the laminating process allows products or wheels to be constructed that have a greater thickness than can be manufactured by die cutting unitary substrates. In the die cutting of unitary substrates, there is a great deal of wasted material and there are limitations of the thickness of the final product that can be manufactured. However, a wheel from a needled substrate is much less susceptible to coming apart during polishing or grinding operations because it is of one piece construction.
A disadvantage of laminated polishing products such as spiral wound wheels is that in the prior art, adhesive has been required to maintain the wheel or polishing product in a wound state. It has been found that the adhesive layers may act as a barrier to uniform wicking of slurries or impregnation in a laminated product and may also pick up particles of the article being worked or large particles of abrasives and scratch the surface of the article being polished or ground.
In one conventional process of manufacturing spiral wound polishing wheels, a layer of fibrous substrate material is provided with an adhesive applied to one side of the material. The material is then tightly wound and the roll is placed in an oven for a period of time to allow the adhesive to cure. The roll material is then sliced and finished. Another known process of manufacturing a spiral wound polishing wheel is to cast a film of resin on a sheet of silicone paper. Then a fibrous substrate material is provided and the film is laid down on one side of the substrate. The roll is wound so that the film of adhesive is between adjacent layers of the roll. After processing, wheels are then cut from the roll. Both of these methods of forming a spiral wound wheel suffer from the disadvantages discussed above.